Speed Sensorless Fault Tolerant Control for DC Servo Motor with Current Sensor Fault

– This paper discusses the application of a fault tolerant control scheme in sensorless speed control for dc motors. The sensorless speed system works by estimating the speed using the current measurement value. The novelty of the proposed scheme is a speed estimator capable of accommodating current sensor faults, which is the only measurement information. The technique used is a modification of the Extended State Observer (ESO) where the residual is not only used to estimate the state, but also to estimate the load torque. In this case, the load torque is treated as a changing input parameter and it is estimated using the observer's normal approach. The modified ESO estimation result is in the form of speed and current estimate, and then fed to the state feedback control with the integrator in order to maintain the speed at the setpoint value. In order to test the proposed control system, numerical simulations are carried out and comparisons are made between the control system with ESO and with modified ESO. From the results of this simulation experiment, the conclusion is that the modified ESO control system is proven to be able to overcome changes in load torque and setpoint as well as sensor faults that occur.